Re: [matplotlib-devel] imshow without resampling in the ps backend.

[Jae-Joon L. <lee...@gm...>]

On Thu, Dec 17, 2009 at 5:03 PM, Andrew Straw <str...@as...> wrote:
> It's not clear to me if this proposal lets one specify any arbitrary affine
> transformation. Does it?

I believe it does. 3 coordinates will define 6 equations where we have
6 unknowns of the affine matrix.
The question is how user want to specify the transform.
The extended extent keyword would be useful for the cases like the
pseudo-perspective projection that you mentioned. But, it will not be
very convenient for the cases like simple rotation.


>
> In general -- very nice. Thanks.
>
> In specific, I think the way you have already implemented things is
> sufficient. I think if a user can write a little helper function (as in your
> demo) to avoid a dumbed-down API being part of MPL, that would be best.
> Anyone specifying their own affine transform is probably going to want a
> pretty precise level of control, anyway. (Of course if your extent keyword
> proposal is already a general purpose API, then please ignore this comment.)

I, personally, don't like the idea that user needs to define his/her
own transform to rotate/skew the image. Rotation and skew seems more
like properties of the image, rather than the transform.

Anyhow, unless others step in, I may leave it as is (partially because
I don't have much use case for rotated/skewed images for now). And, I
hope someone implement similar affine transform for other backends.
For the backends that requires resampling (agg, etc.), it might be
better if the affine transform is taken care during the resampling
(i.e., in the Image.draw method) rather than to be delegated to the
backends.

Regards,

-JJ

>
> -Andrew
>